Controllable airflow modification device periodic load control

ABSTRACT

An active wing extension includes a body portion substantially parallel to a wing of an aircraft, as if it were an extension of the wing. The body portion is attachable to an aircraft wing and includes multiple controllable airflow modification devices coupled thereto. By virtue of having multiple controllable airflow modification devices, the wing extension is capable of adjusting control surfaces of the multiple controllable airflow modification devices in response to in-flight conditions, to reduce wing loads, improve wing fatigue characteristics, increase range, reduce torsional loads, alleviate flutter, and/or increase efficiency.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and is a non-provisional of, U.S.Patent Application No. 61/761,187 filed on 5 Feb. 2013, entitled“CONTROLLABLE AIRFLOW MODIFICATION DEVICE PERIODIC LOAD CONTROL,” whichis hereby incorporated by reference in its entirety.

BACKGROUND

There exists an ever growing need in the aviation industry to increaseaircraft efficiencies and reduce the amount of fossil fuels consumed.Winglets have been designed and installed on many aircraft includinglarge multi-passenger aircraft to increase efficiency, performance, andaesthetics. Such winglets usually consist of a horizontal body portionthat may attach to the end of a wing and an angled portion that mayextend vertically upward from the horizontal body portion. For example,a winglet may be attached to a pre-existing wing of an aircraft toincrease flight efficiency, aircraft performance, or even to improve theaesthetics of the aircraft. Similarly, simple wing extensions have beenused to address similar goals.

However, the cost to install a winglet or a wing extension on anaircraft is often prohibitive due to the requirement to reengineer andcertify the wing after the winglet or extension is installed. Thus,aftermarket installation of winglets and wing extensions has generallybeen reserved for large aircraft owned and operated by large aircraftcompanies.

Existing winglets and wing extensions have limited utility, in that eachwinglet and wing extension must be designed and certified for a specificwing of a specific aircraft model. Moreover, addition of a winglet orwing extension to an aircraft typically increases the loads on the wing,thereby decreasing the usable life of the wing and/or requiring additionof substantial structural reinforcement to the wing. The weight of thisstructural reinforcement detracts from any efficiencies gained byaddition of the winglet in the first place. Additionally, existingwinglets and wing extensions, which are fixed, are unable to adapt tochanges in in-flight conditions. Accordingly, there remains a need inthe art for improved aircraft winglets and wing extensions.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

This disclosure describes active airflow modification systems that mayuse multiple controllable airflow modification devices. For example, anaircraft may comprise a fuselage with a baseline wing coupled an activewing extension. The active wing extension may comprise a plurality ofcontrollable airflow modification devices (CAMDs). A CAMD may comprise acontrol surface and a control system for controlling the motion of thecontrol surface based at least in part on in-flight and/or historicalload data. The control system may be configured to control multipleCAMDs independently or in coordination with each other.

Various embodiments provide for a wing extension that is fixedlyattachable to a baseline wing of an aircraft. Here the wing extensionmay comprise a plurality of CAMDs. A CAMD may be coupled to a controlsystem for controlling a control surface of the CAMD. In variousembodiments, the control system may be configured to control a pluralityof CAMDs independently of an auto-pilot and/or a fly-by-wire system ofthe aircraft. The control system may comprise a control device withcontrol logic. The control device may be communicatively coupled to asensor and/or multiple sensors located on the aircraft to receive asignal to indicate flight conditions of the aircraft. The control devicemay be configured to adjust the CAMD at least partly based on the signalfrom the sensor located on the aircraft.

Various embodiments provide for use of an active airflow modificationsystem including a plurality of CAMDs. For example, the system mayreceive flight condition data from a sensor located on an aircraft. Thesystem may adjust a plurality of CAMDs located on a wing extension ofthe aircraft based at least in part on the received flight conditiondata. The CAMDs may be adjusted by, for example, rotating a controlsurface to reduce a wing load of a wing of the aircraft by moving acenter of pressure of the wing, the center of pressure due to andassociated with aerodynamic forces acting on the wing, inboard and/orreduce an impact of a wing extension on a fatigue life of a wing of theaircraft. Additionally or alternatively, the CAMDs may be used to detectand/or respond to periodic loading, for example, aerodynamic flutter aswell as torsion loads. The CAMDs may be adjusted independently of eachother or in coordination with one another.

BRIEF DESCRIPTION OF THE DRAWINGS

The Detailed Description is set forth with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different figures indicates similaror identical items.

FIGS. 1A-C depict an illustrative wing extension with a verticallyextending wingtip device attachable to a wing of an aircraft.

FIGS. 2A-C depict another illustrative wing extension attachable to awing of an aircraft.

FIG. 3 depicts an aircraft with attached illustrative wing extensions,each wing extension having multiple airflow modification devices.

FIGS. 4A-H depict illustrative wing extensions and wingtip devices.

FIGS. 5A-F depict illustrative wing extensions attached to illustrativewings of aircraft.

FIG. 6 depicts the illustrative wing extension with a wingtip device ofFIG. 1A and a cross-sectional view of the wing extension with a wingtipdevice, taken along line A-A of FIG. 6.

FIG. 7 depicts an illustrative cross-section of the wing extension witha wingtip device of FIG. 1A with a mechanical control system.

FIG. 8 depicts an illustrative cross-section of the wing extension witha wingtip device of FIG. 1A with a computer controlled control system.

FIG. 9 depicts a design load comparison graph.

FIG. 10 depicts a design stress and moment load comparison graph.

FIGS. 11A-D depict an illustrative wing extension with a verticallyextending wingtip device, a view from a trailing edge of the wingextension with a wingtip device depicted in FIG. 11A, and across-sectional view of the wing extension with a wingtip device takenalong line C-C of FIG. 11B.

FIGS. 12A-F depict an aircraft with attached illustrative wingextensions according to one embodiment.

FIG. 13 depicts a flowchart illustrating operation of controllableairflow modification devices.

DETAILED DESCRIPTION Overview

This application describes controllable airflow modification devices(CAMDs) that may be used in active wing extensions for improving theefficiency, performance, and/or aesthetics of an aircraft. The CAMDsaccording to this application may also reduce fatigue of the wings ofthe aircraft, extend a usable life of the wings of the aircraft, and/ordecrease a certification cost and time associated with adding wingextensions to the aircraft. Wing extensions may also include wingtipdevices that may further improve efficiency, performance, and aestheticsof an aircraft. By virtue of having CAMDs, such active wing extensionsmay be able to adjust edges and/or portions of the control surfaces of aCAMD in response to flight condition data.

As discussed above, adding wing extensions to an existing wing improvesairplane efficiency and performance by increasing lift and reducingdrag. This performance benefit may come at the cost of adding additionalstress to the wing that was not accounted for by the original airplanemanufacturer. As a result, installing traditional passive wingextensions or winglets on airplanes is expensive because the wing mayneed to be fully analyzed, reverse engineered, and tested to determineif the wing has the structural ability to accommodate the addition ofwinglets. In most cases, when installing conventional winglets or wingextensions, structural wing modifications are required. Additionally,the useful life (fatigue life) of the wing is reduced by addition ofwinglets or wing extensions, thereby increasing the total cost ofairplane ownership to the customer.

Additionally, the dynamic loading of a wing may be affected. Forexample, a wing may be subject to periodic loading or oscillationcommonly referred to flutter as well as other torsional loading. Often,winglet installations change the lift distribution across the span of anairplane wing. This often results in a change in structural loads in thewing during cruise. On some wings, this may result in an increase in thewing torsion, which may be undesirable or unacceptable from a structuralperspective. A response to increased torsional loading is wingreinforcement, which is often heavy due to, for example, the additionalstructure.

In contrast, the active wing extensions described herein reduce theengineering and certification costs associated with addition of wingextensions because the active extensions have a minimal (potentiallyeven beneficial) structural effect while maintaining a positiveaerodynamic effect. In other words, the active wing extensions describedherein improve airplane efficiency and performance by increasing liftand reducing drag, without the drawbacks (e.g., added stress and fatigueand/or reengineering of the wing) associated with conventional fixedwinglets and wing extensions. As previously noted, an active wingextension according to this disclosure may have an airflow controlsystem in the form of one or more CAMDs located on the wing extension. ACAMD located on the wing extension may be adjusted, which may change theaerodynamic forces on the aircraft wing (e.g., to mitigate or offsetstresses on the wing during gusts, maneuvers, and/or turbulent air).

Additionally or alternatively, a CAMD located on the wing extension maybe adjusted, which may change the aerodynamic forces on the aircraftwing (e.g., to mitigate or offset torsional stresses on the wing duringdifferent flight regimes including, but not limited to flutter). Forexample, the CAMD system may detect an increase in torsion and tocompensate for it, relieving the torsion-induced wing loads for enhancedstructural integrity. Flutter may refer to a cyclical, dynamicdeformation of an aerodynamic structure resulting from an interaction ofstructural properties and flight conditions. Flutter is frequentlycatastrophic, since the deformations of the structure may exponentiallyincrease until failure if they occur at certain frequencies. Theinstallation of a winglet can potentially change the structuralproperties of a wing, which may change the wing's natural frequenciesand thus increase the risk of flutter. Frequently, heavy balancingweights may be added to the winglet to passively damp flutter. A CAMDmay be used to detect the onset of flutter and to react to damp itbefore damage to the wing structure occurs.

By detecting and reacting to the dynamic and/or torsional load a CAMDmay provide structural protection with a small amount of additionalinstallation. Also, flutter damping is a consideration when designingairplanes—particularly airplanes designed to cruise at higher speeds.Actively damping flutter with a CAMD may provide an installation withless weight than a passive winglet or wing extension, and potentiallyallow the airplane to fly at higher speeds. Further, actively adjustingwing torsion during cruise may have significant positive impacts on wingintegrity as well as long-term benefits for wing fatigue.

The active wing extension on an aircraft may be designed to keepspanwise section loads at or below originally designed values for agiven wing without a wing extension. Thus, the active wing extension mayeliminate the requirement to have a wing reinforced due to the additionof the wing extension. Additionally, the CAMD of the active wingextension may be configured to reduce the bending moment of the wing bymoving the center of pressure of the wing inboard and/or reduce theimpact of the wing extension on the fatigue life of the wing. Therefore,the addition of the active wing extension may not significantlydecrease, if at all, the service life of the wing and/or the aircraft towhich it is attached. In some instances, addition of an active wingextension may even reduce fatigue and increase an overall service lifeof the wing and/or the aircraft to which it is attached. Additionally,in the same or other instances, addition of an active wing extension mayalso increase the overall capacity of the wing carrying capability ofthe aircraft, thus increasing the aircraft's gross weight potential.

Often various flight conditions including, but not limited to, 1-gflight regimes may cause a torsional loading on a wing such that anamount of structural reinforcement is added to the wing to reduce theaffect of the torsional loading on structural integrity as well asdeformations or movements in the wing. For example, though an aircraftmay be in a 1-g flight regime, the airspeed and weight of the aircraft,among other factors, may cause a torsional load on the wing sufficientto change the effective aerodynamic wash-in and/or wash-out flow overthe wings. This change caused by the torsional load may adversely affectthe efficiency of the aircraft at that flight condition. Additionally oralternatively, the torsional load may cause any wingtip device that ispresent to deflect from its proper alignment. For example, wingtipdevices are often designed for a certain flight condition, for example,an optimized airspeed and altitude. Often, deviation from the optimizedairspeed and/or altitude may cause the wingtip device to perform withless efficiency than designed. Some of these efficiency losses may stemfrom a change in alignment of the wingtip device with the oncoming flowdue to a twist in the wing from a torsional load.

Various embodiments contemplate deploying a CAMD to positions in variousflight conditions to reduce or resolve some or all of these issues. Forexample, a CAMD may be deflected a first amount to a first position in afirst flight condition where, for example, the first flight condition iscausing a torsional load on a wing. Deflection of the CAMD to the firstposition may cause the flow over the wing to cause an aerodynamic forcethat counter acts the torsional load on the wing. Various embodimentscontemplate that counter acting the torsional load of the wing at thefirst flight condition may allow for the removal of previously addedstructural reinforcements and/or the avoidance of adding structuralreinforcements in the first place. Various embodiments contemplate thatuse of a CAMD in this or another fashion may be integrated into theoriginal design of an aircraft, as an aftermarket conversion, or acombination thereof. For example, an aircraft may be designed for agiven flight envelope where a CAMD is not integrated into the aircraft.However, it may be desired to modify the aircraft to perform in adifferent flight envelope. The new flight envelope may requireadditional and/or different wingtip devices, wing extensions, weightreduction, combinations thereof, or other modifications. Variousembodiments contemplate that inclusion of a CAMD may allow the aircraftto perform the different flight envelop with increased efficiency by,for example, reducing the amount of structural reinforcements required.Additionally or alternatively, the integration of a CAMD may allow anaircraft to reach portions of a flight envelope that might not beachievable with traditional methods and existing technology.

Additionally or alternatively, various embodiments contemplate deployinga CAMD to a position to cause a wingtip device to remain in, or closerto, proper alignment. For example, in a given flight condition,aerodynamic loads exerted on a wing may cause a torsional load causing awing to twist. This twist may cause a wingtip device to diverge from apreferred alignment with the wing and the oncoming flow. Variousembodiments contemplate that deploying the CAMD to a position may causean aerodynamic force that may counteract the torsional load. Thiscounteracting force may cancel some or the entire torsional load andallow the wing to reduce or eliminate effective twist in the wing andallow the wingtip device to come closer or return to a preferredalignment with the wing and the oncoming flow.

Often an aircraft is designed to avoid flutter at certain regions of aflight envelope. Often, however, flutter may become critical at aspecific flight conditions and fuel loads. Onset of flutter conditionsis often sensitive to altitude, true airspeed, among other factors. Anoften result of these factors, is that the aircraft is designed to avoidflutter at limited regions of a flight envelope. Additionally,traditional methods of reducing flutter often include adding ballast toportions of the wings. While the additional ballast may be effective atlimiting flutter at certain portions of a flight envelope, theadditional ballast often adds to the overall weight of the aircraft andmay reduce overall efficiency of the aircraft. Additionally, the addedweight from the ballast may cause additional structural reinforcement toportions of the wing to support the increased stresses caused by theballast over the entire flight envelope. This may further reduce theoverall efficiency of the aircraft.

Various embodiments contemplate deploying a CAMD to positions in variousflight conditions to reduce or resolve some or all of these issues. Forexample, a CAMD may be deployed to a substantially static position inorder to change the loading on a wing in a certain flight condition thatmay change the harmonic response of the wing sufficient to avoidentering a flutter condition. This may also allow for the reduction,removal, and/or avoidance of any ballast and supporting structure fromthe aircraft to avoid a critical flutter condition. Additionally oralternatively, this may allow for addressing possible flutter conditionsin multiple, otherwise unaddressed, regions of a flight envelope.

Additionally or alternatively, various embodiments contemplate deployinga CAMD to multiple positions in a periodic fashion in a certain flightcondition. Various embodiments contemplate that the periodic changes inpositions may cause aerodynamic forces that may cancel out partially orentirely and/or disrupt a reinforcing mode of the flutter condition.This may allow the aircraft to avoid entering certain flutterconditions. This may also allow for the reduction, removal, and/oravoidance of any ballast and supporting structure from the aircraft toavoid a critical flutter condition. Additionally or alternatively, thismay allow for addressing possible flutter conditions in multiple,otherwise unaddressed, regions of a flight envelope.

Various embodiments contemplate that use of a CAMD in this or anotherfashion may be integrated into the original design of an aircraft, as anaftermarket conversion, or a combination thereof. For example, anaircraft may be designed for a given flight envelope where a CAMD is notintegrated into the aircraft. However, it may be desired to modify theaircraft to perform in a different flight envelope. The new flightenvelope may require additional and/or different wingtip devices, wingextensions, weight reduction, combinations thereof, or othermodifications. Various embodiments contemplate that inclusion of a CAMDmay allow the aircraft to perform the different flight envelop withincreased efficiency by, for example, reducing the amount of structuralreinforcements required. Additionally or alternatively, the integrationof a CAMD may allow an aircraft to reach portions of a flight envelopethat might not be achievable with traditional methods and existingtechnology. Additionally or alternatively, various embodimentscontemplate that a CAMD may operate independently or in conjunction withother control surfaces of an aircraft.

Additionally or alternatively, various additional external structuresmay be added to an aircraft that may affect the aerodynamics of anaircraft. For example, the addition of an external structure. By way ofexample only, an external structure may comprise an external fuel tank,an external pod. For example, military aircraft often may attachexternal ordnance, countermeasures, gun pods, targeting pods, and/ordrop tanks to the wings. Various embodiments contemplate that theaddition of various external structures to a wing may cause an undesiredperiodic loading at a flight condition. Additionally or alternatively,removal of a various external structures to a wing may cause anundesired periodic loading at a flight condition. Additionally oralternatively, the addition of various external structures to a wing maycause a first undesired periodic loading at a first flight condition andthe removal of the various external structure from a wing may cause asecond undesired periodic loading at a second flight condition. Variousembodiments contemplate that the first undesired periodic loading may bethe same, similar, or different from the second undesired periodicloading. Additionally or alternatively, various embodiments contemplatethat the first flight condition may be the same, similar, or differentfrom the second flight condition.

Various embodiments contemplate that by detecting and reacting to adynamic and/or torsional load a CAMD may provide structural protectionby deflecting a control surface causing an advantageous aerodynamic loadthat may reduce or remove an adverse affect on a wing caused by aperiodic load.

As discussed above, this disclosure describes active airflowmodification systems that may use a single or multiple controllableairflow modification devices. For example, an aircraft may comprise afuselage with a baseline wing coupled to the fuselage at a first end ofthe baseline wing. Additionally or alternatively various embodimentscontemplate that a wing may comprise control surfaces including, but notlimited to, ailerons, flaps, flaperons, spoilers, spoilerons, speedbrakes, leading edge devices, warpable portions, tabs, elevators,elevons, controllable airflow modification devices, or combinationsthereof. For example, the baseline wing may have control surfaces,including for example, an aileron. The aircraft may also comprise a wingextension. The wing extension may comprise a horizontal portion coupledto the baseline wing at a second end such that the horizontal portion isoutboard of the baseline wing. The horizontal portion may besubstantially coplanar with the baseline wing, meaning, for example,that if the baseline wing has a dihedral or anhedral configuration, thehorizontal portion may continue outwardly from the baseline wing at thesame angle continuing the dihedral or anhedral configuration.Additionally or alternatively, the horizontal portion may be set at anangle with respect to the baseline wing, for example, providing dihedralor anhedral at the wing extension with respect to the baseline wing. Thewing extension may also comprise a single or a plurality of controllableairflow modification devices (CAMDs) directly coupled to the horizontalportion of the wing extension. The horizontal portion may also comprisea first horizontal segment and a second horizontal segment where thefirst horizontal segment is disposed between the baseline wing and thesecond horizontal segment. Here, the first horizontal segment may bedirectly coupled to a first CAMD of the plurality of CAMDs, and thesecond horizontal segment may be directly coupled to a second CAMD ofthe plurality of CAMDs. Stated another way, the first horizontal segmentcontaining the first CAMD may be located outboard of the baseline wingand inboard of the second horizontal segment containing the second CAMD.

A CAMD may comprise a control surface disposed at an edge of thebaseline wing. For example, the edge may be a leading edge or a trailingedge. For example, the control surface may be disposed at a trailingedge of the baseline wing, such that the control surface issubstantially parallel to the baseline wing. The CAMD may also comprisea control system for controlling motion of the control surface based atleast in part on in-flight load data. The control surface may beconfigured for the aircraft based at least in part on historical flightdata. The control system may be communicatively coupled to a sensorlocated on the aircraft and configured to receive a signal from thesensor. Further, the control system may be configured to control thecontrol surface of the CAMD independent of a control surface of anotherCAMD. Additionally or alternatively, the control system may beconfigured to control the control surface of the first CAMD synchronouswith the second CAMD.

Various embodiments provide for a wing extension that is fixedlyattachable to a baseline wing of an aircraft. Here the wing extensionmay comprise a horizontal portion that is substantially parallel to thebaseline wing of the aircraft where the horizontal portion may beconfigured to fixedly attach to an outboard portion of the baseline wingof the aircraft. The wing extension may also comprise a plurality ofCAMDs coupled to the horizontal portion of the wing extension. The wingextension may further comprise a wingtip device that may be directlycoupled to an outboard portion of the horizontal portion. In someembodiments, the wingtip device may also include a vertically extendingportion. The vertically extending portion extends at least somewhat inthe vertical direction, but need not be perpendicular to the horizontalportion or to the horizon. In other words, the vertically extendingportion extends from the horizontal portion at an angle including avertical component.

A CAMD may be coupled to a control system for controlling a controlsurface of the CAMD. In various embodiments, the control system may beconfigured to control a CAMD independently of an auto-pilot and/or afly-by-wire system of the aircraft. The control system may comprise acontrol device with control logic where the control device may beconfigured to communicatively couple to a sensor located on theaircraft. The control device may be configured, when coupled to thesensor, to receive a signal from the sensor located on the aircraft toflight conditions of the aircraft. The control device being furtherconfigured to adjust the CAMD at least partly based on the signal fromthe sensor located on the aircraft.

Various embodiments provide for use of an active airflow modificationsystem. For example, the system may receive flight condition data from asensor located on an aircraft. The system may adjust a single or aplurality of CAMDs located on a wing extension of the aircraft based atleast in part on the received flight condition data. In someembodiments, the CAMDs may be located on a horizontal portion of thewing extension that may be substantially parallel to a baseline wing ofthe aircraft. The CAMDs may be adjusted by rotating a control surface ata hinge along a horizontal axis such that an edge of the control surfaceother than the one edge coupled to the hinge moves up or down inrelation to the horizontal portion of the wing extension. The adjustmentof the CAMDs may be configured to reduce a wing load of a wing of theaircraft by moving a center of pressure of the wing inboard and/orreduce an impact of a wing extension on a fatigue life of a wing of theaircraft. Here, for example, the wing load may comprise a bending momentand/or a torsional moment of the wing. Additionally or alternatively,the adjustment of the CAMDs may reduce or suppress dynamic and/orharmonic loading related to flutter. This loading may be a torsionalloading along the longitudinal axis of the wing. For example, thislongitudinal load may cause a first localized portion of the wing totend to pitch up and/or pitch down while a second localized portion ofthe wing may tend to pitch up and/or pitch down to a greater or lesserextent than the first localized portion in phase, out of phase, or at adifferent frequency.

The CAMDs may be adjusted independently of each other or in coordinationwith one another. For example, a first CAMD may be adjusted independentof a second CAMD. Additionally or alternatively, a first CAMD may beadjusted in coordination with a second CAMD. For example, a first CAMDmay be adjusted by providing a first control response, and a second CAMDmay be adjusted by providing a second control response. Variousembodiments provide for a magnitude of the second control response to begreater than a magnitude of the first control response. Variousembodiments provide for a timing of the first control response to belater than a timing of the second control response. Various embodimentsprovide for the first and second CAMDs being present in the same wingextension.

Various embodiments contemplate an embodiment with multiple CAMDs wherea first CAMD may address a first type of loading and a second CAMD mayaddress a second type of loading. For example, an in board CAMD mayaddress a load alleviation with respect to a gust load while an outboardCAMD may address a load alleviation with respect to a torsional loadingor transition to a flutter inducing flight regime, or vice versa.Additionally or alternatively, a single CAMD may address some or allload alleviation with respect to a gust load and a torsional loading ortransition to a flutter inducing flight regime by super positioning ofthe response movements of the CAMD.

Additionally or alternatively, a CAMD response to a flutter conditionmay be a harmonic or periodic movement or displacement of the CAMD, astatic displacement (or a neutral point bias) of the CAMD while theflutter inducing flight conditions are detected, expected, or suspected,or a combination thereof.

Illustrative Active Wing Extensions

FIGS. 1A-C depict an illustrative active wing extension 100 which isattachable to a wing 102 of an aircraft (not shown). In one embodiment,the active wing extension 100 may include a body portion 104 which maybe substantially parallel to a horizontal plane and/or a wing of anaircraft. By way of example only, and not limitation, the active wingextension 100 may also include a wingtip device, for example, an angledportion 106 on the outer side of the body portion 104 and an attachableportion 108 on the inner side of the body portion 104. In this example,the outer and inner sides of the body portion 104 are described withrelation to the wing 102 such that the outer side is further from thewing 102 than the inner side. Additionally, the angled portion 106 maybe substantially vertical in relation to the body portion 104 such thatit projects perpendicularly from the body portion 104. However, in otherembodiments, the angled portion 106 may be configured to project fromthe body portion 104 at angles other than 90 degrees. In yet otherembodiments, the angled portion 106 may be configured to project fromthe body portion 104 at angles which include projecting downward (inrelation to the aircraft). Additionally, although the angled portion 106is described above as projecting from the outer side of the body portion104, the active wing extension 100 may be designed such that the angledportion 106 may project from the middle, or any other location, of thebody portion 104 (i.e., the angled portion 106 may be located at anylocation between the inner and outer sides of the body portion 104).Further, although the angled portion 106 is illustrated in FIG. 1A asprojecting from the outer side of the body portion 104 in a blendedconfiguration with a substantially smooth transition from the bodyportion 104 to the angled portion 106, the transition between the bodyportion 104 and the angled portion 106 need not be blended and/orsmooth. Additionally or alternatively, the angled portion 106 may havemultiple vertical or moveable surfaces that may be substantiallyvertical in certain configurations. Additionally or alternatively, theangled portion 106 may extend above the wing 102, below the wing 102, ora combination there of. Additionally or alternatively, the angledportion 106 may be offset from the end of the wing 102, for example aspart of an outer portion of a spiroid wingtip device. Additionally oralternatively, the body portion 104 and angled portion 106, alone or incombination, may comprise at least a portion of a winglet, end-plate,spiroid, split winglet, fence, rake, swallow tail, or a combinationthereof.

The active wing extension 100 may include a controllable airflowmodification device (CAMD) 110 in the form of one or more controlsurfaces 112 located on the body portion 104 and/or the angled portion106. By further way of example, in one embodiment, the CAMD 110 may belocated on the body portion 104 of the active wing extension 100. Inanother embodiment, the CAMD 110 may be located on the angled portion106 of the active wing extension 100. In yet another embodiment, theCAMD 110 may be located on both the body portion 104 and the angledportion 106 of the active wing extension 100. Further, and by way ofexample only, in the embodiment shown in FIG. 1A, the CAMD 110 is shownlocated on the aft of the active wing extension 100 (i.e., the back-sideor trailing edge of the active wing extension 100 in relation to thefront of an aircraft). In this way, adjustment of the CAMD 110 maychange the angle of the control surface 112 in relation to the aftportion (body portion 104 or angled portion 106) of the active wingextension 100 on which the control surface 112 is located. Additionally,the active wing extension 100 may include two CAMDs 110. However, inother embodiments, more or fewer CAMDs 110 may be used depending on avariety of factors, such as the size of the aircraft and desiredperformance characteristics.

Further, as shown in FIGS. 1A and C by way of example only, the angledportion 106 is shown as a basic trapezoidal shape. However the angledportion 106 may be rectangular, triangular, oval, or any other geometricshape. Additionally, the airflow control surface 112 located on theangled portion 106, may be similar in shape to, or the same shape as,the airflow control surface 112 located on the body portion 104 of theactive wing extension 100.

Additionally, the active wing extension 100 in FIGS. 1A and Cillustrates, by way of example and not limitation, one or more sensors114 located in the body portion 104 on the active wing extension 100.However, the one or more sensors 114 may be disposed at other locationsof the active wing extension 100 or of the aircraft. For example, one ormore sensors may be located on the angled portion 106, on the front orleading edge of the body portion 104 (in relation to the aircraft), onthe aft of the body portion 104 (in relation to the aircraft), on thesurface of the wing extension 100, inside the wing extension 100 (i.e.,located within the surface of the wing extension 100), anywhere withinthe aircraft, including, for example, the baseline wing, the fuselage,the tail, or the like.

Also depicted in FIG. 1B, by way of example only, is an illustrativewing 102 of an aircraft (not shown) prior to the attachment of an activewing extension 100 as described above. The wing 102 may include anaileron 116 and a flap 118. The aileron 116 and the flap 118 may be usedfor flight control of the aircraft and in some instances may becontrolled by one or more pilots of the aircraft. The wing 102 may bedescribed as a baseline wing of an aircraft (not shown). The baselinewing may or may not include wingtips and/or wingtip devices that may bereplaced by a wing extension 100 or extended outwardly by a wingextension 100.

FIG. 1A also depicts an illustrative modified wing 120 which may includethe illustrative wing 102 coupled to the active wing extension 100. Themodified wing 120 may be designed and crafted for a new aircraft (e.g.,with an active wing extension integrated into the aircraft during itsoriginal manufacture), or the active wing extension 100 may be attachedto the existing wing 102 after the fact. The active wing extension 100of modified wing 120 may be configured in a similar shape as theexisting wing 102. Additionally, and by way of example only, the wingextension 100 may fit over a portion of the existing wing 102 such thata portion of the end of the existing wing 102 resides within theattachable portion 108 of the active wing extension 100. In that case,the attachable portion 108 may include a sleeve or collar that fits overat least a portion of the end of the existing wing 102. In otherembodiments, the active wing extension 100 may additionally oralternatively be attached to the existing wing 102 by fastening the endof the existing wing 102 to the attachable portion 108 via an abuttingface and/or via an internal structural support. Further, the wingextension 100 may be fabricated of the same or similar material as theexisting wing 102.

FIGS. 2A-C depict an illustrative active wing extension 200 which may beattachable to a wing 102 of an aircraft. In one embodiment, the activewing extension 200 may include a body portion 202 which may besubstantially parallel to a horizontal plane and/or a wing of theaircraft. By way of example only, and not limitation, the active wingextension 200 may also include a wingtip device (not shown) and anattachable portion 204 on the inner side of the body portion 202. Inthis example, the outer and inner sides of the body portion 202 aredescribed with relation to the wing 102 such that the outer side isfurther from the wing 102 than the inner side.

The active wing extension 200 may include a CAMD 206 in the form of oneor more control surfaces 208 located on the body portion 202. By way ofexample only, in the embodiment shown in FIGS. 2A-C, the CAMD 206 isshown located on the aft of the active wing extension 200 (i.e., theback-side or trailing edge of the active wing extension 200 in relationto the front of an aircraft). In this way, adjustment of the CAMD 206may change the angle of the control surface 208 in relation to the aftportion (body portion 202) of the active wing extension 200.Additionally, as discussed below, the active wing extension 200 mayinclude two or more CAMDs 206. However, in other embodiments, more orfewer CAMDs 206 may be used depending on a variety of factors, such asthe size of the aircraft and desired performance characteristics.

Additionally, the active wing extension 200 in FIGS. 2A-C illustrates,by way of example and not limitation, one or more sensors 210 located inthe body portion 202 on the active wing extension 200. However, the oneor more sensors 210 may disposed at other locations of the active wingextension 200 or of the aircraft. For example, one or more sensors maybe located on the front or leading edge of the body portion 202 (inrelation to the aircraft), on the aft of the body portion 202 (inrelation to the aircraft), between the aft and the leading edge of thebody portion 202 (in relation to the aircraft), on the surface of thewing extension 200, inside the wing extension 200 (i.e., located withinthe surface of the wing extension 200), anywhere within the aircraft,including, for example, the baseline wing, the fuselage, the tail, thelike, or a combination thereof.

Also depicted in FIGS. 2A-C, by way of example only, is an illustrativewing 102 of an aircraft (not shown) prior to the attachment of an activewing extension 200 as described above. The wing 102 may include anaileron 116 and a flap 118. The aileron 116 and the flap 118 may be usedfor flight control of the aircraft and in some instances may becontrolled by one or more pilots of the aircraft. The wing 102 may bedescribed as a baseline wing of an aircraft (not shown). The baselinewing may or may not include wingtips and/or wingtip devices that may bereplaced by a wing extension 200 or extended outwardly by a wingextension 200. Additionally, the wing extension 200 may be configured tocouple to the structure of the baseline wing, for example, the wingextension 200 may have one or more spar extensions (not shown) thatcouple to one or more spars in the baseline wing.

FIGS. 2A-C also depict an illustrative modified wing 212 which mayinclude the illustrative wing 102 coupled to the active wing extension200. The modified wing 212 may be designed and crafted for a newaircraft (e.g., with an active wing extension integrated into theaircraft during its original manufacture), or the active wing extension200 may be attached to the existing wing 102 after the fact. The activewing extension 200 of modified wing 212 may be configured in a similarshape as the existing wing 102. Additionally, and by way of exampleonly, the wing extension 200 may fit over a portion of the existing wing102 such that a portion of the end of the existing wing 102 resideswithin the attachable portion 204 of the active wing extension 200. Inthat case, the attachable portion 204 may include a sleeve or collarthat fits over at least a portion of the end of the existing wing 102.In other embodiments, the active wing extension 200 may additionally oralternatively be attached to the existing wing 102 by fastening the endof the existing wing 102 to the attachable portion 204 via an abuttingface and/or via an internal structural support. Further, the wingextension 200 may be fabricated of the same or similar material as theexisting wing 102.

Illustrative Aircraft with Active Wing Extension

FIG. 3 depicts an illustrative load alleviation system 300 implementedon an aircraft 302 that includes at least one attached active wingextension 304. The components of the load alleviation system 300 mayinclude sensors 314, active wing extension(s) 304, a control system 306,CAMD(s) 318, and control surface(s) 312. By way of example only, and notlimitation, FIG. 3 illustrates an active wing extension 304 on each wingof the aircraft 302. However, active wing extensions 304 may also beplaced on other surfaces of the aircraft 302. For example, the activewing extensions 304 may be located on the wings, as shown, or they maybe located on the tail wings, or any other horizontal or verticalsurface of the aircraft 302 including the fuselage.

As mentioned above, the load alleviation system 300 may comprise acontrol system 306. The control system 306 may be configured to controlthe active wing extensions 304 of the aircraft 302. By way of exampleonly, and not limitation, the control system 306 may include one or moreprocessor(s) 308 for receiving and processing system data, including,but not limited to, flight condition data. In one embodiment, theprocessor(s) 308 may receive in-flight data from the sensors 314. Asmentioned above with respect to FIGS. 1A-C and sensors 114, sensors 314may be located anywhere on the aircraft including the wing, fuselage,wing extensions, and/or wingtip devices. The control system 306 mayadditionally consist of memory 310 for the storage of flight conditiondata. The data stored in the memory 310 may include previously receivedflight condition data, currently recorded (i.e., current in-flight)flight condition data, or a compilation of current in-flight data and/orpreviously recorded in-flight data. By way of example only, the memory310 of the control system 306 may include an operating system 312 andcontrol logic 316.

The operating system 312 may be responsible for operating the controlsystem 306 by way of interfacing the data with the processor(s) 308 andproviding a user interface (not shown) for interaction with one or morepilots of the aircraft 302. Additionally or alternatively, the operatingsystem 312 may be responsible for operating the control system 306 byway of interfacing the data with the processor(s) 308 without providinga user interface and may be effectively invisible to a user, forexample, a pilot. The control logic 316 of the control system 306 may beconfigured to operate the control surface(s) 312 of the CAMD(s) 318 ofthe active wing extension 304. In one embodiment, the control logic 316may control the control surface(s) 312 based on flight condition datareceived from the sensor(s) 314. Additionally, parameters 320 may bestored in the memory 310. The parameters may be predetermined parametersand may be used by the control logic 316 to determine operation of thecontrol surface(s) 312. In some embodiments, the control system 306 mayoperate the control surfaces 312 simultaneously or independently. By wayof example only, the control system 306 of FIG. 3 is illustrated in thefuselage and/or hull of the aircraft 302. However, the control system306 can be located anywhere on the aircraft, including, but not limitedto, the cockpit, the tail, the wing, the wing extension, wingtipdevices, or the like.

As mentioned above, the load alleviation system 300 may comprise activewing extension(s) 304, which include CAMD(s) 318 and control surface(s)312. In various embodiments, an active wing extension 304 may containmultiple CAMDs 318 with multiple control surfaces 312. For example, FIG.3 illustrates an aircraft 302 with an active wing extension 304comprising two CAMDs 318 where each CAMD 318 is associated with acontrol surface 312.

Illustrative Airflow Modification Device Configurations

FIGS. 4A-H depict various illustrative embodiments of wing extensionsand/or wingtip replacements, CAMDs, and wingtip devices. For example,FIG. 4A shows CAMD 400, which may comprise a horizontal section 402 thatmay also act as a wing extension to a wing or another extension. CAMD400 may also comprise a wingtip device 404, for example, a winglet. Thewingtip device 404 may be integrated into a CAMD 400 or may be separatefrom CAMD 400. CAMD 400 may also comprise a sensor 406 to provide flightdata to a control system 408. Control system 408 may comprisecontroller(s) (not shown) and actuator(s) (not shown) configured tocontrol a control surface 410. The control surface 410, as discussedabove with respect to control surface 112, may be moved to with respectto the aft portion of the horizontal section 402. CAMD 400 may alsocomprise, as discussed above with respect to body portion 104, anattachable portion 412 on the inboard side of the horizontal section402.

FIGS. 4B-E show various illustrative embodiments of wing extensions withCAMDs integrated into the wing extensions. For example, FIG. 4B shows awing extension 414 that may comprise a CAMD 416. The CAMD 416 maycomprise a control system 408 and control surface 410. Control surface410 may take various forms and span various distances of a wingextension. Wing extensions 414, 418, 420, and 422 show some of thepossible configurations of control surface 410. For example, wingextension 414 comprises a control surface 410 that spans a length lessthan the full length of the wing extension 414 with a section of thewing extension 414 at each end of the control surface 410. The sectionof the wing extension 414 at each end of the control surface 410 may be,but need not be, equal in size. Various embodiments contemplatedifferent sizes of control surfaces 410. For example, a control surface410 used to address torsional loading and/or flutter reduction may havea smaller or larger surface area than a control surface 410 used toaddress gust load alleviation.

FIG. 4C shows wing extension 418 comprising a control surface 410spanning a length less than the full length of the wing extension 418with a section of the wing extension 418 at one end of the controlsurface 410, for example on an inboard end of the wing extension 418.FIG. 4D shows wing extension 420 comprising a control surface 410spanning the full length of the wing extension 420. FIG. 4E shows wingextension 422 comprising a control surface 410 spanning a length lessthan the full length of the wing extension 422 with a section of thewing extension 422 at one end of the control surface 410, for example onan outboard end of the wing extension 422.

Though FIG. 4D shows control surface 410 as roughly wedge shaped, thecontrol surface need not follow the profile of an airfoil. For example,the control surface may be a substantially planar.

FIGS. 4F-G show wing extensions that may comprise multiple CAMDsintegrated into an extension. For example, FIG. 4F shows wing extension424, which may comprise two CAMDs 416. FIG. 4G shows wing extension 426,which may comprise three CAMDs 416. The number of CAMDs integrated intoa wing extension is not necessarily limited to three. The number ofCAMDs may depend upon the aircraft, aircraft configuration, mission,operational environment, desired performance parameters, manufacturingtechniques and materials, and hardware, among others. Additionally, asdiscussed below, multiple wing extensions with one or more CAMDs may beused in coordination with each other to achieve a desired configurationwhile maintaining a degree of modularity.

FIG. 4H also shows various wingtip devices including a winglet 428 and awingtip 430. Wingtip devices may include, but are not limited to,winglets, fences, spiroids, raked wingtips, squared-off tips, aluminumtube bow, rounded, Hoerner style, drooped tips, tip tanks, sails, andend plates. Wingtip devices may be used in conjunction with active wingextensions. In some cases, use of an active wing extension may enableuse of wingtip devices that the original aircraft was not originallycapable of using, for example, winglets. Additionally or alternatively,wingtip devices may or may not include control surfaces, where thecontrol surfaces may or may not be active control surfaces.

The sizing of a CAMD for an aircraft may depend on various factors. Forexample, the profile of a CAMD or wing extension housing the CAMD maysubstantially match the airfoil shape 432 and chord 434 of the wing atthe point of attachment. In various embodiments this may provide asubstantially smooth transition from the baseline wing to the wingextension. However, various embodiments contemplate a disjunctiveintersection between the baseline wing and the CAMD or wing extensionhousing the CAMD. Further, the CAMD or wing extension housing the CAMDmay be configured to support effective wing twist across the CAMD orwing extension housing the CAMD.

Additionally, the spanwise length of the wing extension may be based inpart on the aircraft, size, structure, configuration, speed, mission,performance, desired performance, and desired mission.

The number of CAMDs that may be integrated into the system may be basedon the spanwise length of the wing extension as well as theaforementioned factors. The number of CAMDs desired may also depend onthe gross weight of an aircraft. For example, one set of CAMDs may besufficient for a relatively light aircraft of less than 10,000 lbsoperating at relatively low speeds of around 150 knots. Additionally,two or more sets of CAMDs may be preferred for an aircraft greater than10,000 lbs.

Other factors that may influence the number of CAMDs may be the sizingof the CAMDs including, but not limited to, the control surface size,deflection angle, resulting hinge moment at operating speed of theaircraft and deflection angle, and motor/actuator power and authority.

The control surface size of a CAMD may comprise a chord wise length thatmay be measured in percentage of the wing extension chord. This valuemay range from 100% of the wing extension chord (where the entire chordlength of the wing extension moves as part of the control surface) to asmall percentage, less than 1% of the wing extension chord. In variousembodiments, it a control surface may be configured to have a chordlength in similar proportion to an adjacent or nearby control surface ofthe baseline wing, for example, an aileron.

The spanwise length or width of a CAMD may be based on theaforementioned factors as well. Additionally, the spanwise length orwidth of a CAMD may be based on manufacturing and modularityimplications as well. For example, a CAMD may be configured with a setwidth. This may represent a balance of the aforementioned factors. Forexample, it may be possible to select a motor of sufficient power andresponse time to move a control surface sufficiently fast to effect adesired response or movement.

Illustrative Multiple Controllable Airflow Modification DeviceConfigurations

FIGS. 5A-F depict various illustrative embodiments of wings, wingextensions and/or wingtip replacements, CAMDs, and wingtip devices. Forexample, FIG. 5A shows a baseline wing 500 comprising a wing section 502and a wingtip device 504. The baseline wing 500 may or may not includewingtips and/or wingtip devices that may be replaced by a wing extensionor extended outwardly by a wing extension.

Various embodiments of active wing extensions contemplate changing thebaseline wing 500 from an initial configuration to a modifiedconfiguration that may incorporate multiple CAMD(s). For example, FIG.5B shows a modified wing 506 comprising a wing section 502 and wingextension 424. As discussed above with respect to FIG. 4, wing extension424 comprises multiple CAMDs, for example, two. Modified wing 506 may ormay not integrate a wingtip device. For example, modified wing 506 mayintegrate a squared-off or rounded-off wingtip configuration.

FIG. 5C shows modified wing 508 comprising a wing section 502 and wingextensions 414. In this embodiment, two wing extensions 414 are coupledtogether adjacent to each other. This approach may create a singleeffective wing extension built from otherwise modular wing extensions414. As discussed above with respect to FIG. 4, wing extension 414comprises a CAMD. Additionally, modified wing 508 may comprise a wingtipfeature. In this case, a preexisting wingtip feature 504 may be used.

FIG. 5D shows modified wing 510 comprising a wing section 502 and wingextensions 414 adjacent to each other. Here, modified wing 510 maycomprise a wingtip feature, for example winglet 512.

FIG. 5E shows modified wing 514 comprising a wing section 502 and wingextensions 414 adjacent to each other. Here, modified wing 514 maycomprise a wingtip feature, for example CAMD 400. As discussed abovewith respect to FIG. 4, CAMD 400 may comprise a wing extension as wellas a wingtip device. In this case, CAMD 400 provides both a wingextension as well as a winglet. This configuration may provide threeCAMDs per modified wing 514.

FIG. 5F shows modified wing 516 comprising a wing section 502 and wingextensions 518 and 520 adjacent to each other. Here, the planformgeometry of a baseline wing, for example, a taper from root to tip, ifpresent, may be extended through the wing extensions 518 and 520. Forexample, wing extension 520 may be smaller in planform area whencompared to wing extension 518 since wing extension 520 is outboard ofwing extension 518 with respect to the baseline wing 502.

As discussed above, a wide range in the number of CAMDs andconfiguration of CAMDs are possible. This may allow for flexibility andmodularity of a system. This may also lead to a lower number of baseparts, configurations, and certifications that may be required thanwould a system that did not provide modularity and created a customsystem for each new configuration.

Illustrative Airflow Modification Devices

FIG. 6 depicts the active wing extension 100 of FIG. 1A and includes anend view 600 of the active wing extension 100, taken along line A-A. Theend view 600 runs across the body portion 104 of the wing extension 100.Additionally, the end view 600 of the body portion 104 of the wingextension 100 illustrates one embodiment of the components of thecontrol system 306 of FIG. 3 located in the active wing extension 100.As shown in FIG. 6, the control system 306 may be located in the bodyportion 104 of the wing extension 100; however, the control system 306may be located in the angled portion 106 of FIGS. 1A and C of the wingextension 100, in other portions of the active wing extension 100, or inany location on the aircraft, including, for example, the fuselage. Thecontrol system 306 may also be distributed over various portions of theCAMD, wing extension, and/or aircraft.

In one embodiment, by way of example only, the control system 306 may becommunicatively and/or mechanically coupled to the control surface 112by way of a connection 602. FIG. 3 illustrates the connection 602 as onesubstantially straight coupling from the control system 306 to thecontrol surface 112. However, the connection 602 may bend, turn, pivot,or be a series of multiple connections to make the connection 602. Theconnection 602 between the control system 306 and the control surface112 may be operable by electronic, mechanic, or any other resource forcoupling the control surface 112 to the control system 306. The controlsurface 112 may be coupled to the active wing extension 100 by a hinge,pivot, or other swivel device 604 to allow the control surface 112 torotate the aft end up and/or down in relation to the body of the activewing extension 100. As noted above, to the commands given by the controlsystem 306 to operate the control surface 112 of the active wingextension may be based on the flight condition data received by thecontrol system 306 from the sensors 114 on the aircraft 302.

FIG. 7 illustrates one embodiment 700 of the control system 306 as seenthrough the end view 600 of active wing extension 100. As discussed withreference to FIGS. 3 and 6, the control system 306 may control thecontrol surface 112 of the active wing extension 100 based on flightcondition data. The control system 306 may be coupled to the controlsurface 112 which may be illustrative of the airflow modification device110 illustrated in FIG. 1C. The control surface 112 may be coupled tothe active wing extension 100 by a hinge, pivot, or other swivel device304 to allow the control surface 112 to move in relation to the commandsgiven by the control system 306.

Additionally, by way of example only, FIG. 7 depicts an illustrativeembodiment of a mechanical control system 702. The mechanical controlsystem 702 may include of a bob weight 704 coupled to a spring 706. Thebob weight 704 may be fabricated of lead, or any other weight which mayactivate the mechanical control system 702. The spring 706 may be madeof coil springs, bow springs, or any other device used to createresistance for the bob weight 704. In one embodiment, and by way ofexample only, the bob weight 704 may be coupled to the control surface112 by way of a coupling system 708. By way of example only, couplingsystem 708 may be a rigid object, belt, chain, or other resource forcoupling the bob weight 704 to the control surface 112. The couplingsystem 708 is illustrated by way of example only, with two connectionpoints 710 and 712, and one fixed point 716. The coupling system 708 mayalso contain a series of pivot points, angles, or other connections. Thecoupling system 708 may be configured to connect to spring 706 at thepoint 714.

In one embodiment, the mechanical system 702 may be configured to reactto in-flight conditions, for example, a gust of wind, maneuvers producedby one or more pilots, or any other condition on the wing of theaircraft. Based on the in-flight conditions, the bob weight 704 maychange position within the mechanical system 702 relative to the spring706. For example, the bob weight 704 may drop, rise, or otherwise changelocation, depending on the in-flight conditions. When the bob weight 704changes location, it may cause the coupling system 708 to initiate aresistance force on the spring 706 causing connection point 710 to move.Consequently, motion of the connection point 710 may adjust connectionpoints 712 such that the coupling system 708 causes the connection 604to adjust the control surface 112.

FIG. 8 illustrates an additional embodiment 800 of a logical controlsystem 802 as seen through the end view 600 of active wing extension100. As discussed with reference to FIGS. 3, 6, and 7, the logicalcontrol system 802, much like the control system 306 of FIG. 7, maycontrol the control surface 112 of the active wing extension 100 basedon flight condition data. By way of example, and not limitation, theembodiment 800 of FIG. 8 may include one or more sensors 114, a logicalcontroller 804, and an actuator, for example, motor 806. The sensors 114may be representative of the sensors illustrated in FIG. 1C. The sensors114 may be electronically coupled to the logical controller 804. Thelogic controller 804 may be coupled to the motor 806. The motor 806, byway of example only, may be an electric motor. In one example, the motor806 may be coupled to the control surface 112. The motor 806 may be ableto rotate the aft portion of the control surface 112 up or down,depending on the received in-flight conditions and the predeterminedflight conditions programmed into the logical controller 802.Additionally, the motor 806 may be coupled to the control surface 112 byway of electronic, pneumatic, hydraulic, or another resource foractuating the control surface 112. In at least one embodiment, and byway of example only, the motor 806 may cause the control surface 112 topivot on an axis, moving the aft portion up and or down to adjust thecontrol surface 112 as calculated by the logical controller 802.

The logical controller 804 may be located in the active wing extension100, the cockpit (not shown), the main fuselage of the aircraft (notshown), or anywhere located in or on the aircraft. Flight condition datamay be first received by the sensors 114 located on the aircraft 302.The information may be resulting from deliberate in-flight maneuvers bya pilot, gusts of wind, or other causes of change in conditions to theaircraft. Information gathered by the sensors 114 may be received by thelogical controller 804 and the data may be analyzed or otherwiseprocessed. In one example, the logical controller 804 may be programmedwith predetermined flight conditions which may be representative of aspecific make and model of the aircraft. Additionally, the logicalcontroller 804 may calculate the position of the control surface 112based on the in-flight conditions to minimize the moment load on thewing. In other words, the logical controller 804 may receive thein-flight conditions and determine the needed position of the controlsurface 112. Additionally, the logic controller 804 may send a signal tothe motor 806 to which it may be coupled to effectuate control of thecontrol surface 112. By way of example only, the motor 806 may beelectronic, pneumatic, hydraulic, or any other type of motor.

Illustrative Comparison Graphs

FIG. 9 illustrates a graph 900 which compares the local normalized liftcoefficient or lift distribution on a wing of an aircraft in relation tothe location on the wing of the aircraft. The wing of FIG. 9 is ageneral representation of a wing and is not made representative of aspecific make or model of an aircraft wing. The X-axis of the graph isillustrative of the location on the wing. It is represented inpercentage (%) of the semi-span of the wing. The length of the wing isonly a representation and is not limiting of the size of the wing onwhich an active wing extension 100 may be installed. The Y-axis isrepresentative of the lift distribution on the wing. The load is higherthe closer to the center of the airplane. The graph 900 is forillustrative purposes only, and illustrates one example of the loaddistribution which an aircraft may experience. The graph 900 is notrestrictive of whether or not the distributed load may be more or lessat any point on the graph. The graph 900 is representative of the basicshape of the distributed load a wing may encounter.

The graph 900 illustrates the lift distribution on a traditionalmanufactured wing, which is represented by the line on the graph 900with a dash and two dots. The graph 900 also illustrates the liftdistribution on the wing when a traditional wing extension with awingtip device, for example, a winglet, is installed, which isrepresented by the dashed line. Additionally, the graph 900 illustratesthe lift distribution on the wing when an active wing extension 100 witha wingtip device is incorporated on the wing.

The comparison illustrates that the lift distribution caused by thetraditional wing extension with a wingtip device, for example, awinglet, may be greater at the wingtip. This may move the center of liftof the wing outboard which may increase the wing bending loads. However,when the wing has an active wing extension 100 utilizing the loadalleviation system 300 the lift distribution at the wingtip may dropsignificantly lower than that of a traditional winglet. The graph 900illustrates that the load may even drop below zero at the location ofthe wingtip (the point furthest away from the aircraft). These loads arerepresentative of the design load on the aircraft, which is the highestload an aircraft may see.

When the active wing extension controllable surfaces 112 are undeployed,the active wing extension 100 produces the same efficiency benefits of apassive or fixed winglet. When the local normalized lift coefficientincreases and the loads on the wing increase, the control surfaces 112on the wing extension 100 may adjust to reduce the loads on the wing. Inone embodiment, the airflow control surfaces 112 may be undeployed orundeflected the majority of the time. However, in another embodiment,they may only be deployed when the load on the wing approaches theoriginal design loads.

FIG. 10 illustrates a graph 1000 representing a wing design stresscomparison of active wing extension systems, a wing with a winglet withno active system, and a standard wing. The design stress or design loadis the critical load to which the wing structure is designed to carry.The X-axis represents the location along the length of an aircraft'swing. The unit is shown in percentage (%) of wing semi-span. The lengthof the wing is only a representation and is not limiting of the size ofthe wing on which an active wing extension 100 may be installed.Additionally, in FIG. 10, the Y-axis represents the load on the wing.This load is illustrative of the design root bending moment load. Thecomparison shows the standard load that the wing bears. The graph 1000is for illustrative purposes only and is not meant to be restrictive inany way. The root bending moment load may be greater or smaller forvarying wing makes and models. The graph 1000 also shows the load of awing when a wing extension and/or winglet is added with no activesystems. The graph 1000 additionally shows the loads on the wing when awing extension and/or winglet is added to the wing.

With the load alleviation system 300 enabled on the wing extension 100the design moment loads may be lower than the design loads on the wingwith a winglet with no active system. Additionally, with the loadalleviation system 300 enabled on the wing extension 100, the momentloads may be lower than the loads on the wings with no wing extensionsand/or winglets installed. Traditional winglets and extensions increasewing stress, as a function of load factor, and substantially reduce thefatigue life of the wing. The slope of the “stress per g” curve isnormally linear and the addition of passive winglets increases the slopewhich reduces the expected life and calculated life of the wing. Activewing extensions reduce the slope of this curve so that it is the same orlower than the slope of the original curve.

Illustrative Control of Airflow Modification Devices

As discussed above, a controller may receive in flight data reflecting acurrent flight condition the aircraft may be encountering, for example,a gust, maneuver, or entering a flight regime where flutter may occur.This data may be provided by a sensor within the aircraft and may beconverted into or received by the controller in the form of flightcondition data. Based on this data, a controller may cause a controlsurface to move, if desirable, to respond to the current flightcondition. For example, if an aircraft encounters a gust in the verticaldirection, the sensor may sense the gust, for example, through a changein voltage from an accelerometer, and transmit that data to acontroller. The controller may receive this data and adjust one or moreCAMDs of a wing extension. The adjustment may cause a control surface ofa CAMD to deflect reducing the lift generated by the wing extension.

Additionally or alternatively, if the aircraft begins to encounter aflight regime where flutter may occur, a first sensor may detect achange in voltage from an accelerometer or strain gauge indicating avertical movement in a first direction while a second sensor may detecta change in voltage from an accelerometer or strain gauge indicating avertical movement in a second direction. In various situations this mayindicate a torque or torsion along the wing. This indication may berelated to a pitching and/or plunging motion inherent to flutter. Thecontroller may receive this data and adjust one or more CAMDs of a wingextension. The adjustment may cause a control surface of a CAMD todeflect reducing the torque generated by the wing extension, wing,and/or flight regime.

Additionally or alternatively, various embodiments contemplate detectingtorsion using linear and/or rotational sensors, micro load cells and/orstrain gages mounted on the structure of the wing, and/or accelerometersmounted at multiple points in the wing and/or wing extension.Additionally or alternatively, sensors may also include, but are notlimited to, strain gages installed on the wing spars to detect changesin moment and torsion, accelerometers mounted in the forward and aftportions of the wings to detect “pitching and plunging” motion inherentto flutter, pressure and temperature sensors to detect flying conditionsof the airplane, and/or linear and rotational position sensors to detectdeformations of the wing.

The system may use a leading-edge and/or a trailing-edge aerodynamicsurfaces on the horizontal or vertical portion of the winglet to alterairflow around the CAMD installation to mitigate increased torsion. Thesurfaces used to mitigate torsion may be the existing load alleviationsurfaces, or may be smaller, independent surfaces designed specificallyto address torsion.

Additionally or alternatively, flutter may be dampened using these samesurfaces, or may use surfaces designed to generate specific forces.These surfaces may be simple flaps, or may resemble speed brakes or dragrudders. Flutter damping may also be achieved using a small, movingobject of mass inside the structure of the wing or winglet which mayoscillate out of phase with flutter and/or change positions to tune theresponse of the wing to flutter-inducing conditions.

To assist an active system, additional passive features may also beincluded. For example, these features may include gurney flaps, airfoilmodifications in certain wing regions, additional vertical surfaceseither above or below the chordline of the wing, forward sweep of partor all of the vertical surface or surfaces, among other features.

In various embodiments and flight regimes, the reaction time may impactthe effectiveness of a CAMD at alleviating loads on wing extensioncaused by gusts, maneuvers, and/or flutter inducing flight regimes. Byway of a non-limiting example, CAMDs according to this application maybe configured to provide an initial response of a controller within 10milliseconds (ms) of detection of a gust, maneuver, and/or torque, andto complete an initial movement of a control surface of the CAMD within500 ms of the detection. In various embodiments, a controller accordingto this application may be configured to cause a control surface tobegin moving within 8 ms of a detection of a disturbance and complete aninitial movement of a control surface within 100 ms. Various embodimentsmay contemplate quicker or slower response and completion times.

Control of multiple CAMDs in a wing extension may be independent of eachother, or control of the CAMDs may be coordinated. For example,independent control of each CAMD in a wing extension may provide for asimultaneous response and deployment of each CAMD. In that case, acontrol system or control systems responding to the same in-flight datamay cause similar CAMDs to have similar or the same responses. Inembodiments where wing extensions have more than one CAMD, controlfactors may be configured to be adjustable. Those control factors mayinclude initial values, thresholds, and initial response settings toaddress the number and responsiveness of individual CAMDs.

Various embodiments provide for coordinated responses of multiple CAMDsof a wing extension. The coordinated response may comprise causing themultiple CAMDs to respond at the same time. As a non-limiting example, awing extension having two CAMDs may be configured to deploy the CAMDs ina coordinated and synchronized response where both CAMDs initiallydeploy at the same time. In that case, the CAMDs may be deployed by asame or different deflection. In various embodiments, a wing extensionhaving two CAMDs may be configured to cause a first CAMD located inboardof a second CAMD to initially deploy with a smaller deflection than thesecond CAMD. Additionally or alternatively, the wing extension havingtwo CAMDs may be configured to cause the first CAMD located inboard of asecond CAMD to initially deploy with a larger deflection than the secondCAMD.

Additionally or alternatively, the coordinated response may comprisecausing the multiple CAMDs to respond at staged or staggered times. Forexample, the first CAMD that is located inboard of the second CAMD mayinitially deploy after the second outboard CAMD. The second CAMD maydeploy if/when a gust or maneuver exceeds a first load factor/stressthreshold. The first CAMD may deploy subsequent to the deployment of thesecond CAMD if/when a gust or maneuver exceeds a second higher loadfactor/stress threshold. The first and second load factor/stressthresholds may be configured to maintain spanwise section loads and/ortorsional loads at or below originally designed values for a given wingwithout a wing extension.

Additionally or alternatively, the first CAMD that is located inboard ofthe second CAMD may initially deploy before the second outboard CAMD.The first CAMD may deploy if/when a gust or maneuver exceeds a firstload factor/stress threshold. In this case, the second CAMD may deploysubsequent to the deployment of the first CAMD if/when a gust ormaneuver exceeds a second higher load factor/stress threshold. The firstand second load factor/stress thresholds may be configured to maintainspanwise section loads and/or torsional loads at or below originallydesigned values for a given wing without a wing extension.

Further, as an illustrative and non-limiting example, in variousembodiments contemplating a coordinated deployment of multiple CAMDs,deployment of the second CAMD to a greater degree when compared to thefirst CAMD may be thought of as a coarse response. Further, thedeployment of the first CAMD to may be thought of as a fine or vernieradjustment.

Further, as an illustrative and non-limiting example, in variousembodiments contemplating a coordinated deployment of multiple CAMDs,where deployment of the first CAMD addresses a first type of loading,for example, a gust and/or maneuver load, and where deployment of thesecond CAMD addresses a second type of loading, for example a torsionalload.

FIGS. 11A-D depict an illustrative embodiment where multiple CAMDs arecoordinated in their deployment. FIG. 11A shows an active airflowmodification system 1100 that may be implemented on an aircraft (notshown) having a wing 1102. The active airflow system may comprise a wingextension 1104 comprising a first CAMD 1106 and a second CAMD 1108. Thefirst CAMD 1106 may be located outboard of the second CAMD 1108 withrespect to the wing 1102. The first CAMD 1106 may comprise a controller(not shown) and a control surface 1110 while the second CAMD 1108 maycomprise a controller (not shown) and a control surface 1112.

As discussed above, in various embodiments, wing extension 1104 may beconfigured to cause the first CAMD 1106 to deploy control surface 1110to a greater degree/magnitude/deflection when compared to the controlsurface 1112 of the second CAMD 1108.

FIGS. 11B-D show three additional views of the active airflowmodification system 1100. For example, FIG. 11B depicts a view of theactive airflow system 1100 from the trailing edge of the wing 1102 andwing extension 1104. FIG. 11C depicts a view of the active airflowmodification system 1100 along the C-C view plane shown in FIG. 11B.FIG. 11C also depicts a controller 1114 of CAMD 1108 that may causecontrol surface 1112 to deploy. FIG. 11C depicts a view of the activeairflow modification system 1100 along the C-C view plane shown in FIG.11B where control surface 1112 is deployed to a first position 1116 atan angle θ (theta) as measured from an undeployed position 1118. FIG.11C also shows control surface 1110 deployed to a second position 1120at an angle φ (phi) as measured from an undeployed position 1118.

Illustrative Sensor Placement on a Wing and Active Wing Extensions

FIGS. 12A-F depict illustrative embodiments of wings and wing extensionswith sensor locations. For example, FIG. 12A depicts an illustrativeactive airflow modification device 1200 that includes at least twosensors 1210 fore and aft of an illustrative torsional axis 1212.

FIG. 12B shows an embodiment with multiple sensors 1210 are located onin and/or on the airflow modification device 1200. It is contemplatedthat one or more sensors may be located at the various locations.Additionally or alternatively, not all of the indicated locations ofsensors 1210 may be occupied with sensors. For example, variousembodiments contemplate that only sensors 1210A and 1210B are presentand or used. Various embodiments contemplate that additional sensors, ifpresent, may provide a backup to and/or a confirmation indication for aprimary set of sensors.

FIG. 12C shows an embodiment where sensors 1210 need not be located at asame spanwise location. For example, a sensor 1210A may be locatedfurther from an aircraft center line than a sensor 1210B.

FIG. 12 D shows another embodiment where sensors 1210 are located atdifferent spanwise locations.

FIG. 12E shows an embodiment where sensors 1210 may be located atvarious locations along a wing and/or wing extension. Similar to FIG.12B, FIG. 12E shows example locations of sensors 1210, where some, all,or other different locations of sensors 1210 may be present.

FIG. 12F shows an embodiment where a first sensor 1210A may be presenton a first airflow modification device 1218 and a second sensor 1210Bmay be located on a second airflow modification device 1220. Thecombination of these sensor 1210 may be used to detect a torque and oran onset of a flutter condition.

Illustrative Methods

FIG. 13 is a flowchart of one illustrative method 1300 of operating acontrollable airflow modification devices. As discussed above thesensors receive data based on the flight conditions of the aircraft. Themethod may, but not necessarily, be implemented by using sensors andcontrol systems described herein. For ease of understanding, the method1300 is described in the context of the configuration shown in FIGS. 3and 11A-D. However, the method 1300 is not limited to performance usingsuch a configuration and may be applicable to other aircraft and othertypes of wing extensions.

In this particular implementation, the method 1300 begins at block 1302in which a control system, such as control system 306, receives datafrom one or more sensors, such as sensors 314, located in or on theaircraft 302. The data received from the sensors may comprise flightcondition data that may include, but is not limited to, in-flight loadfactor data, airspeed data, aircraft weight data, and/or altitude data.The flight condition data may be representative of various flightconditions resulting in various loads experienced on the aircraft 302.By way of example only, the various loads on the aircraft may be relatedto a gust loading, a torsional loading, and/or a transition to a flutterinducing flight regime.

At block 1304, one or more CAMDs may be adjusted. Adjustment of theCAMDs 318 may be based in part on the data received at block 1302. Forexample, flight condition data is received as a signal and interpretedby control logic 316 using parameters 320. The control logic 316 maydetermine operation of the control surface(s) 312, such as determining aposition or positions to deploy the control surface(s) 312. For example,the control logic 316 may determine that a control surface 1110 shouldbe deployed to position 1120 as shown in FIG. 11D. Control logic 316 maygenerate a signal to cause the control surface to move.

At block 1306, the signal from control logic 316 is received by anactuator or controller, for example controller 1114 as shown in FIG.11C. The actuator or controller may then actuate and/or cause a controlsurface to deploy. In various embodiments, the control surface isdeployed by rotating at a hinge along a rotational axis. For example,controller 1114 may cause control surface 1112 to deploy to position1116. Control surface may be adjusted to position 1116 from anotherposition. For example, control surface 1112 may initially be at an anglegreater or less than θ (theta) and deployed to position 1116.

In various embodiments, method 1400 is repeated to provide adjustmentsof the multiple CAMDs over the course of a flight accounting for changesin the flight condition and loads on the aircraft.

Various embodiments of method 1300 provide for adjusting CAMDs of aplurality of CAMDs independently of other CAMDs. For example, at block1304, control logic 316 may be configured to determine a position of acontrol surface of a first CAMD of the plurality of CAMDs independent ofa control surface of a second CAMD of the plurality of CAMDs. At block1306, based in part on the control logic 316, a first CAMD of theplurality of CAMDs is adjusted independent of a second CAMD of theplurality of CAMDs. In some cases, this may cause the first and secondCAMDs to react in substantially the same manner since each CAMD mayreact independently to the same flight condition data.

Various embodiments of method 1300 provide for adjusting the pluralityof CAMDs in coordination with one another. For example, at block 1304,control logic 316 may be configured to determine a position of a controlsurface of a first CAMD of the plurality of CAMDs in coordination with acontrol surface of a second CAMD of the plurality of CAMDs. At block1306, based in part on the control logic 316, a first CAMD of theplurality of CAMDs may be adjusted in coordination with a second CAMD ofthe plurality of CAMDs. In various embodiments the magnitude ofresponses between the CAMDs of the plurality of the CAMDs may bedifferent. For example, adjusting a first CAMD of the plurality of CAMDsprovides a first control response. Adjusting a second CAMD of theplurality of CAMDs provides a second control response.

In some instances the magnitude of the second control response may begreater than the first control response. For example, control logic 316may provide a first signal causing control surface 1110 of the firstCAMD 1106 to move to position 1120 at an angle φ (phi) measured fromundeployed position 1118 generating a first control response. Controllogic 316 may also provide a second signal causing control surface 1112of the second CAMD 1108 to move to position 1116 at an angle θ (theta)measured from undeployed position 1118 generating a second controlresponse. In various embodiments, angle φ (phi) may be greater or lessthan angle θ (theta). In various embodiments, angle φ (phi) may begreater than zero, while angle θ (theta) may be substantially equal tozero. Additionally or alternatively, angles φ (phi) and θ (theta) may bethe same or substantially similar configuring at least a subset of theplurality of CAMDs to act synchronously.

In various embodiments and configurations, coordinated control asdiscussed above may be configured to cause an outboard CAMD to provide acoarse adjustment, which may comprise a larger initial response, whilean inboard CAMD provides a fine adjustment, which may comprise a smallerinitial response when compared to the initial response of the outboardCAMD. An example of this may be seen in FIGS. 11A-D. Additionally oralternatively, an inboard CAMD may be configured to provide a coarseadjustment and an outboard CAMD may be configured to provide a fineadjustment.

CONCLUSION

Although embodiments have been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the disclosure and appended claims are not necessarily limited tothe specific features or acts described. Rather, the specific featuresand acts are disclosed as illustrative forms of implementing theembodiments. For example, the methodological acts need not be performedin the order or combinations described herein, and may be performed inany combination of one or more acts.

What is claimed is:
 1. An aircraft comprising: a fuselage; a baselinewing, the baseline wing coupled to the fuselage at a first end of thebaseline wing and having an aileron; and a wing extension comprising: ahorizontal portion coupled to a second end of the baseline wing, suchthat the horizontal portion is outboard of the baseline wing; and acontrollable airflow modification device (CAMD) directly coupled to thehorizontal portion of the wing extension, the CAMD being configured toalleviate a cyclical load on a wing based at least in part ondisplacement changes in a configuration of the CAMD, the displacementchanges based at least in part on detecting a flutter condition of theaircraft based at least in part on data received from one or moresensors located on the aircraft.
 2. The aircraft of claim 1, the CAMDcomprising: a control surface disposed at a trailing edge of the wingextension, such that the control surface is substantially parallel tothe baseline wing; and a control system for controlling motion of thecontrol surface based at least in part on in-flight load data.
 3. Theaircraft of claim 2, the control surface being configured for theaircraft based at least in part on historical flight data.
 4. Theaircraft of claim 2, the control system being communicatively coupled toone or more sensors located on the aircraft and configured to receive asignal from the one or more sensors located on the aircraft.
 5. Theaircraft of claim 4, wherein the one or more sensors comprise a firstsensor fore of a torsional axis of the wing extension and a secondsensor aft of the torsional axis of the wing.
 6. The aircraft of claim4, wherein the one or more sensors comprise a rotational sensor.
 7. Theaircraft of claim 1, the displacement changes comprising a harmonicdisplacement change in a configuration of the CAMD, a periodicdisplacement change in a configuration of the CAMD, a static change in aconfiguration of the CAMD, or combinations thereof.
 8. A wing extensionfixedly attachable to a baseline wing of an aircraft, the wing extensioncomprising: a horizontal portion that, when attached to the aircraft, issubstantially parallel to the baseline wing of the aircraft, thehorizontal portion being configured to fixedly attach to an outboardportion of the baseline wing of the aircraft; and a controllable airflowmodification device (CAMD) coupled to the horizontal portion of the wingextension, the CAMD being configured to alleviate a flutter condition onthe baseline wing based at least in part on displacement changes in aposition of a control surface of the CAMD, the displacement changesbased at least in part on a received signal from one or more sensors,the received signal indicating a flutter inducing flight condition. 9.The wing extension of claim 8, the CAMD being coupled to a controlsystem for controlling a control surface of the CAMD.
 10. The wingextension of claim 9, the control system being configured to control theCAMD independently of one or more of an auto-pilot or a fly-by-wiresystem of the aircraft.
 11. The wing extension of claim 9, the controlsystem comprising a control device with control logic, the controldevice being configured to communicatively couple to one or more sensorslocated on the aircraft.
 12. The wing extension of claim 11, the controldevice being configured, when coupled to the one or more sensor, toreceive a signal from the one or more sensors located on the aircraft toindicate a flutter inducing flight condition of the aircraft.
 13. Theaircraft of claim 8, the displacement changes comprising a harmonicdisplacement change in a configuration of the CAMD, a periodicdisplacement change in a configuration of the CAMD, a static change in aconfiguration of the CAMD, or combinations thereof.
 14. A methodcomprising: receiving flight condition data from two or more sensorslocated on an aircraft; and alleviating a flutter condition based atleast in part on adjusting a plurality of controllable airflowmodification devices (CAMDs) located on a wing extension of the aircraftbased at least in part on the received flight condition data, theplurality of CAMDs located on a horizontal portion of the wing extensionthat is substantially parallel to a baseline wing of the aircraft, theplurality of CAMDs controllable independently of a control surface ofthe baseline wing, the adjusting the plurality of CAMDs comprising:detecting a flight condition that induces flutter; and harmonicallydisplace a control surface of the CAMD, statically displace a controlsurface of the CAMD, or a combination thereof.